Tri -Acetate base and polyester base both have advantages and disadvantages.
The biggest drawback of polyester in a camera film ( and usually one of its advantages ) is its incredible strength, especially in motor driven cameras, in our humble opinion.
Polyester builds charge quicker than tri-acetate.
Polyester is relatively cheap compared to tri-acetate film base.
As an FYI to PE
We do coat on tri-acetate and on polyester base and on the same machine ( M14 Mobberley ). With film, paper as well as inkjet emulsions.
As I am sure you are aware we have two completely different coating and preparations procedures for doing so.
Polyester especially unsubbed is a super efficient light pipe.
Polyester is superb if you need a thinner substrate ( surveillance / aeriel etc ).
Polyester is very stable.
Polyester is readily available, from a range of manufacturers.
Simon ILFORD Photo / HARMAN technology Limited :